Nicotinic acetylcholine receptor sub-type selective amides of diazabicycloalkanes

ABSTRACT

Compounds, pharmaceutical compositions including the compounds, and methods of preparation and use thereof are disclosed. The compounds are amide compounds which can be prepared from certain heteroaryl carboxylic acids and certain diazabicycloalkanes. The compounds exhibit selectivity for, and bind with high affinity to, neuronal nicotinic receptors of the α4β2 subtype in the central nervous system (CNS). The compounds and compositions can be used to treat and/or prevent a wide variety of conditions or disorders, particularly CNS disorders. The compounds can: (i) alter the number of nicotinic cholinergic receptors of the brain of the patient, (ii) exhibit neuroprotective effects, and (iii) when employed in effective amounts, not result in appreciable adverse side effects (e.g. side effects such as significant increases in blood pressure and heart rate, significant negative effects upon the gastrointestinal tract, and significant effects upon skeletal muscle).

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/342,635, filed Jan. 3, 2012, which is a divisional of U.S. patentapplication Ser. No. 12/447,850, filed Aug. 18, 2009, now U.S. Pat. No.8,114,889 issued Feb. 14, 2012, which claims priority to PCT ApplicationNumber PCT/US2007/083330, with an International Filing Date of Nov. 1,2007, which claims priority to U.S. Provisional Patent Application Ser.No. 60/856,079, filed Nov. 2, 2006, each of which is herein incorporatedby reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to compounds that bind to and modulate theactivity of neuronal nicotinic acetylcholine receptors, to processes forpreparing these compounds, to pharmaceutical compositions containingthese compounds and to methods of using these compounds for treating awide variety of conditions and disorders, including those associatedwith dysfunction of the central nervous system (CNS).

BACKGROUND OF THE INVENTION

The therapeutic potential of compounds that target neuronal nicotinicreceptors (NNRs), also known as nicotinic acetylcholine receptors(nAChRs), has been the subject of several recent reviews (see Breininget al., Ann. Rep. Med. Chem. 40: 3 (2005), Hogg and Bertrand, Curr. DrugTargets: CNS Neurol. Disord. 3: 123 (2004), Suto and Zacharias, ExpertOpin. Ther. Targets 8: 61 (2004), Dani et al., Bioorg. Med. Chem. Lett.14: 1837 (2004), Bencherif and Schmitt, Curr. Drug Targets: CNS Neurol.Disord. 1: 349 (2002)). Among the kinds of indications for which NNRligands have been proposed as therapies are cognitive disorders,including Alzheimer's disease, attention deficit disorder andschizophrenia (Newhouse et al., Curr. Opin. Pharmacol. 4: 36 (2004),Levin and Rezvani, Curr. Drug Targets: CNS Neurol. Disord. 1: 423(2002), Graham et al., Curr. Drug Targets: CNS Neurol. Disord. 1: 387(2002), Ripoll et al., Curr. Med. Res. Opin. 20(7): 1057 (2004), andMcEvoy and Allen, Curr. Drug Targets: CNS Neurol. Disord. 1: 433(2002)); pain and inflammation (Decker et al., Curr. Top. Med. Chem.4(3): 369 (2004), Vincler, Expert Opin. Invest. Drugs 14(10): 1191(2005), Jain, Curr. Opin. Inv. Drugs 5: 76 (2004), Miao et al.,Neuroscience 123: 777 (2004)); depression and anxiety (Shytle et al.,Mol. Psychiatry 7: 525 (2002), Damaj et al., Mol. Pharmacol. 66: 675(2004), Shytle et al., Depress. Anxiety 16: 89 (2002));neurodegeneration (O'Neill et al., Curr. Drug Targets: CNS Neurol.Disord. 1: 399 (2002), Takata et al., J. Pharmacol. Exp. Ther. 306: 772(2003), Marrero et al., J. Pharmacol. Exp. Ther. 309: 16 (2004));Parkinson's disease (Jonnala and Buccafusco, J. Neurosci. Res. 66: 565(2001)); addiction (Dwoskin and Crooks, Biochem. Pharmacol. 63: 89(2002), Coe et al., Bioorg. Med. Chem. Lett. 15(22): 4889 (2005));obesity (Li et al., Curr. Top. Med. Chem. 3: 899 (2003)); and Tourette'ssyndrome (Sacco et al., J. Psychopharmacol. 18(4): 457 (2004), Young etal., Clin. Ther. 23(4): 532 (2001)).

A limitation of some nicotinic compounds is that they are associatedwith various undesirable side effects, for example, by stimulatingmuscle and ganglionic receptors. It would be desirable to havecompounds, compositions and methods for preventing and/or treatingvarious conditions or disorders (e.g., CNS disorders), includingalleviating the symptoms of these disorders, where the compounds exhibitnicotinic pharmacology with a beneficial effect (e.g., upon thefunctioning of the CNS), but without significant associated sideeffects. It would further be highly desirable to provide compounds,compositions and methods that affect CNS function without significantlyaffecting those receptor subtypes which have the potential to induceundesirable side effects (e.g., appreciable activity at cardiovascularand skeletal muscle sites). The present invention provides suchcompounds, compositions and methods.

SUMMARY OF THE INVENTION

The present invention provides certain amide compounds which can beformed from certain heteroaryl carboxylic acids and certaindiazabicycloalkanes, particularly 3,7-diazabicyclo[3.3.0]octane and3,7-diazabicyclo[3.3.1]nonane. These amide compounds bind with highaffinity to NNRs of the α4β2 subtype, found in the CNS, and exhibitselectivity for the α4β2 subtype over the α7 NNR subtype, also found inthe CNS. The present invention also relates to pharmaceuticallyacceptable salts prepared from these compounds and the pharmaceuticalcompositions thereof, which can be used for treating and/or preventing awide variety of conditions or disorders, and particularly thosedisorders characterized by dysfunction of nicotinic cholinergicneurotransmission or the degeneration of the nicotinic cholinergicneurons. Also provided are methods for treating and/or preventingdisorders, such as CNS disorders, and also for treating certainconditions (e.g., alleviating pain and inflammation), in mammals in needof such treatment. The methods involve administering to a subject atherapeutically effective amount of the compounds (including salts) orpharmaceutical compositions including such compounds. Further providedis a method for treatment of disorders selected from the groupconsisting of age-associated memory impairment, mild cognitiveimpairment, pre-senile dementia (early onset Alzheimer's disease),senile dementia (dementia of the Alzheimer's type), Lewy body dementia,vascular dementia, Alzheimer's disease, stroke, AIDS dementia complex,attention deficit disorder, attention deficit hyperactivity disorder,dyslexia, schizophrenia, schizophreniform disorder, and schizoaffectivedisorder. Even further provided is a method for treatment of disordersselected from the group consisting of the treatment of mild to moderatedementia of the Alzheimer's type, attention deficit disorder, mildcognitive impairment and age associated memory impairment.

The pharmaceutical compositions incorporate a compound of the presentinvention which, when employed in effective amounts, interacts withrelevant nicotinic receptor sites of a subject, and hence acts as atherapeutic agent to treat and prevent a wide variety of conditions anddisorders. The pharmaceutical compositions provide therapeutic benefitto individuals suffering from such disorders and exhibiting clinicalmanifestations of such disorders, in that the compounds within thosecompositions, when employed in effective amounts, can (i) exhibitnicotinic pharmacology and affect relevant nicotinic receptors sites(e.g., act as a pharmacological agonist to activate nicotinicreceptors), and/or (ii) elicit neurotransmitter secretion, and henceprevent and suppress the symptoms associated with those diseases. Inaddition, the compounds have the potential to (i) increase the number ofnicotinic cholinergic receptors of the brain of the patient, (ii)exhibit neuroprotective effects, and/or (iii) when employed in effectiveamounts, to not cause appreciable adverse side effects (e.g.,significant increases in blood pressure and heart rate, significantnegative effects upon the gastro-intestinal tract, and significanteffects upon skeletal muscle). The pharmaceutical compositionscomprising the compounds of the invention, are believed to be safe andeffective with regards to prevention and treatment of a wide variety ofconditions and disorders.

The foregoing and other aspects of the present invention are explainedin detail in the detailed description and examples set forth below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a chart showing the results of a study on object recognitionin rats treated orally withN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane. Theresults are shown as a function of recognition index (%) versus dose(mg/kg).

FIG. 2 is a chart showing the results of a study on object recognitionin rats treated orally withN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane. Theresults are shown as a function of recognition index (%) versus dose(mg/kg).

DETAILED DESCRIPTION

The subtype selective compounds, pharmaceutical compositions includingthese compounds, methods of preparing the compounds, and methods oftreatment and/or prevention using the compounds are described in detailbelow.

The compounds and methods described herein will be better understoodwith reference to the following preferred embodiments. The followingdefinitions will be useful in defining the scope of the invention:

In this specification, unless stated otherwise, the term “alkyl”includes both straight and branched chain alkyl groups. These may be,but are not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl,i-butyl, s-butyl, t-butyl, n-pentyl, i-pentyl, neo-pentyl, n-hexyl ori-hexyl. The term “C₁₋₄ alkyl” thus includes alkyl groups having 1 to 4carbon atoms, including, but are not limited to, methyl, ethyl,n-propyl, i-propyl or tert-butyl.

In this specification, unless stated otherwise, the term “cycloalkyl”refers to an optionally substituted, partially or completely saturatedmonocyclic, bicyclic or bridged hydrocarbon ring system. The term “C₃₋₈cycloalkyl” may be, but is not limited to cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

As used herein, heterocyclyl radicals contain from 3 to 10 membersincluding one or more heteroatoms selected from oxygen, sulfur andnitrogen. Examples of suitable heterocyclyl moieties include, but arenot limited to, piperidinyl, morpholinyl, pyrrolidinyl, imidazolidinyl,pyrazolidinyl, isothiazolidinyl, thiazolidinyl, isoxazolidinyl,oxazolidinyl, piperazinyl, oxanyl (tetrahydropyranyl), and oxolanyl(tetrahydrofuranyl).

As used herein, C₁₋₆ alkoxy radicals contain from 1 to 6 carbon atoms ina straight or branched chain, and also include C₃₋₆ cycloalkoxy radicalsand alkoxy radicals that contain C₃₋₆ cycloalkyl moieties. Examplesinclude, but are not limited to methoxy, ethoxy, propoxy, isopropoxy,butoxy, t-butoxy, isobutoxy, cyclopropylmethoxy, allyloxy orpropargyloxy.

As used herein, “aromatic” refers to 3 to 10, preferably 5 and6-membered ring aromatic and heteroaromatic rings.

As used herein, “aromatic group-containing species” refers to moietiesthat are or include an aromatic group. Accordingly, phenyl and benzylmoieties are included in this definition, as both are or include anaromatic group, and pyridinyl and pyrimidinyl are included in thedefinition, as both are heteroaromatic, a subset of aromatic.

As used herein, aryl radicals are selected from phenyl, naphthyl andindenyl.

As used herein, heteroaryl radicals contain from 3 to 10 members,preferably 5 or 6 members, including one or more heteroatoms selectedfrom oxygen, sulfur and nitrogen. Examples of suitable 5-membered ringheteroaryl moieties include furanyl, thienyl, pyrrolyl, imidazolyl,oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, tetrazolyl,triazolyl, and pyrazolyl. Examples of suitable 6-membered heteroarylmoieties include pyridinyl, pyrimidinyl, pyrazinyl, and pyridazinyl.Examples of 9-membered heteroaryl groups include benzimidazolyl,indolizinyl, indolyl, purinyl and indolinyl. Examples of 10-memberedheteroaryl groups include quinolinyl and isoquinolinyl.

It will be appreciated that throughout the specification, the number andnature of substituents on rings in the compounds of the invention willbe selected so as to avoid sterically undesirable combinations.

Certain compound names of the present invention were generated with theaid of computer software (ACDLabs 8.0/Name(IUPAC)).

Examples of suitable pharmaceutically acceptable salts include inorganicacid addition salts such as chloride, bromide, sulfate, phosphate, andnitrate; organic acid addition salts such as acetate, galactarate,propionate, succinate, lactate, glycolate, malate, tartrate, citrate,maleate, fumarate, methanesulfonate, p-toluenesulfonate, and ascorbate;salts with acidic amino acid such as aspartate and glutamate; alkalimetal salts such as sodium salt and potassium salt; alkaline earth metalsalts such as magnesium salt and calcium salt; ammonium salt; organicbasic salts such as trimethylamine salt, triethylamine salt, pyridinesalt, picoline salt, dicyclohexylamine salt, andN,N′-dibenzylethylenediamine salt; and salts with basic amino acid suchas lysine salt and arginine salt. The salts may be in some caseshydrates or ethanol solvates. Representative salts are provided asdescribed in U.S. Pat. No. 5,597,919 to Dull et al., U.S. Pat. No.5,616,716 to Dull et al. and U.S. Pat. No. 5,663,356 to Ruecroft et al.

The compounds of Formula I and pharmaceutically acceptable salts thereofmay exist in solvated, for example hydrated, as well as unsolvatedforms, and the present invention encompasses all such forms.

As used herein, an “agonist” is a substance that stimulates its bindingpartner, typically a receptor. Stimulation is defined in the context ofthe particular assay, or may be apparent in the literature from adiscussion herein that makes a comparison to a factor or substance thatis accepted as an “agonist” or an “antagonist” of the particular bindingpartner under substantially similar circumstances as appreciated bythose of skill in the art. Stimulation may be defined with respect to anincrease in a particular effect or function that is induced byinteraction of the agonist or partial agonist with a binding partner andcan include allosteric effects.

As used herein, an “antagonist” is a substance that inhibits its bindingpartner, typically a receptor. Inhibition is defined in the context ofthe particular assay, or may be apparent in the literature from adiscussion herein that makes a comparison to a factor or substance thatis accepted as an “agonist” or an “antagonist” of the particular bindingpartner under substantially similar circumstances as appreciated bythose of skill in the art. Inhibition may be defined with respect to adecrease in a particular effect or function that is induced byinteraction of the antagonist with a binding partner, and can includeallosteric effects.

As used herein, a “partial agonist” or a “partial antagonist” is asubstance that provides a level of stimulation or inhibition,respectively, to its binding partner that is not fully or completelyagonistic or antagonistic, respectively. It will be recognized thatstimulation, and hence, inhibition is defined intrinsically for anysubstance or category of substances to be defined as agonists,antagonists, or partial agonists.

As used herein, “intrinsic activity” or “efficacy” relates to somemeasure of biological effectiveness of the binding partner complex. Withregard to receptor pharmacology, the context in which intrinsic activityor efficacy should be defined will depend on the context of the bindingpartner (e.g., receptor/ligand) complex and the consideration of anactivity relevant to a particular biological outcome. For example, insome circumstances, intrinsic activity may vary depending on theparticular second messenger system involved. See Hoyer, D. and Boddeke,H., Trends Pharmacol. Sci. 14(7): 270-5 (1993). Where such contextuallyspecific evaluations are relevant, and how they might be relevant in thecontext of the present invention, will be apparent to one of ordinaryskill in the art.

As used herein, modulation of a receptor includes agonism, partialagonism, antagonism, partial antagonism, or inverse agonism of areceptor.

As used herein, neurotransmitters whose release is mediated by thecompounds described herein include, but are not limited to,acetylcholine, dopamine, norepinephrine, serotonin and glutamate, andthe compounds described herein function as modulators at the α4β2subtype of the CNS NNRs.

Compounds

The compounds described herein are amide compounds formed from certainheteroaryl carboxylic acids and certain diazabicycloalkanes. Thesecompounds can be represented as Formula I:

wherein n has the value of 0 or 1, and Cy is a heteroaryl group chosenfrom the group of 2-furanyl, 3-furanyl, 2-oxazolyl, 4-oxazolyl,5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl,1,3,4-oxadiazol-2-yl, 1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl,2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isothiazolyl, 4-isothiazolyl,5-isothiazolyl, 1,3,4-thiadiazol-2-yl, 1,2,4-thiadiazol-3-yl,1,2,4-thiadiazol-5-yl and 4-pyridinyl, which heteroaryl groups areoptionally substituted with up to three non-hydrogen substituentsindependently selected from C₁₋₆ alkyl, substituted C₁₋₆ alkyl, C₂₋₆alkenyl, substituted C₂₋₆ alkenyl, C₂₋₆ alkynyl, substituted C₂₋₆alkynyl, C₃₋₈ heterocyclyl, substituted C₃₋₈ heterocyclyl, C₃₋₈cycloalkyl, substituted C₃₋₈ cycloalkyl, C₅₋₁₀ aryl, C₅₋₁₀ heteroaryl,substituted C₅₋₁₀ aryl, substituted C₅₋₁₀ heteroaryl, C₁₋₆ alkyl-C₅₋₁₀aryl, C₁₋₆ alkyl-C₅₋₁₀ heteroaryl, substituted C₁₋₆ alkyl-C₅₋₁₀ aryl,substituted C₁₋₆ alkyl-C₅₋₁₀ heteroaryl, C₅₋₁₀ aryl-C₁₋₆ alkyl, C₅₋₁₀heteroaryl-C₁₋₆ alkyl, substituted C₅₋₁₀ aryl-C₁₋₆ alkyl, substitutedC₅₋₁₀ heteroaryl-C₁₋₆ alkyl, halo, —OR′, —NR′R″, —CF₃, —CN, —NO₂, —C₂R′,—SR′, —N₃, —C(═O)NR′R″, —NR′C(═O)R″, —C(═O)R′, —C(═O)OR′, —OC(═O)R′,—OC(═O)NR′R″, —NR′C(═O)OR″, —SO₂R′, —SO₂NR′R″, and —NR′SO₂R″, where R′and R″ are independently selected from hydrogen, C₁₋₆ alkyl, C₃₋₈cycloalkyl, C₃₋₈ heterocyclyl, C₅₋₁₀ aryl, C₅₋₁₀ heteroaryl or C₅₋₁₀aryl-C₁₋₆ alkyl, or R′ and R″ and the atoms to which they are attachedtogether can form a C₃₋₈ heterocyclic ring, wherein the term“substituted”, as applied to alkyl, alkenyl, alkynyl, heterocyclyl,cycloalkyl, aryl, heteroaryl, alkylaryl, alkylheteroaryl, arylalkyl andheteroarylalkyl, refers to substitution by one or more alkyl, aryl,heteroaryl, halo, —OR′ and —NR′R″ groups, or pharmaceutically acceptablesalts thereof.

One embodiment of the invention relates to compounds of Formula Iwherein n has the value of 0 or 1, and Cy is a C₅₋₁₀ heteroaryl groupchosen from the group of 2-furanyl or 3-furanyl, 2-oxazolyl, 4-oxazolyl,5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl,1,3,4-oxadiazol-2-yl, 1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl,2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isothiazolyl, 4-isothiazolyl,5-isothiazolyl, 1,3,4-thiadiazol-2-yl, 1,2,4-thiadiazol-3-yl,1,2,4-thiadiazol-5-yl and 4-pyridinyl, which heteroaryl groups areoptionally substituted with up to three non-hydrogen substituentsindependently selected from C₁₋₆ alkyl, substituted C₁₋₆ alkyl, halo,and C₂₋₆ alkynyl substituted with phenyl.

In one embodiment n is 0. In another embodiment n is 1. In a furtherembodiment Cy is 2-furanyl. In yet another embodiment Cy is 2-furanylsubstituted with halo. In one embodiment Cy is 2-furanyl substitutedwith chlorine. In yet a further embodiment n is 0 and Cy is 2-furanyloptionally substituted with halo. In one embodiment n is 1 and Cy is2-furanyl optionally substituted with halo. In yet another embodiment2-furanyl is substituted on position 5. In another embodiment R′ and R″are independently selected from methyl, ethyl, n-propyl, isopropyl,n-butyl, i-butyl, s-butyl or t-butyl. In a further embodiment R′ and R″are independently selected from phenyl or benzyl.

In some cases, compounds of the present invention are chiral. Thepresent invention includes all enantiomeric or diastereomeric forms ofsuch compounds.

Representative compounds of the present invention include the following:

-   N-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(3-methylfuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(5-methylfuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(3-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(3-bromofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(5-bromofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(4-phenylfuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(5-(2-pyridinyl)furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(5-(phenylethynyl)furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(furan-3-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(oxazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(oxazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(oxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(isoxazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(isoxazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(isoxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(3-bromoisoxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(3-methoxyisoxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(1,2,4-oxadiazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(1,2,4-oxadiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(1,3,4-oxadiazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(thiazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(thiazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(thiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(isothiazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(isothiazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(isothiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(1,2,4-thiadiazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(1,2,4-thiadiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(1,3,4-thiadiazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   N-(pyridin-4-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane,-   and pharmaceutically acceptable salts thereof.

Representative compounds of the present invention also include thefollowing:

-   N-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(3-methylfuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(5-methylfuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(3-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(3-bromofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(5-bromofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(4-phenylfuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(5-(2-pyridinyl)furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(5-(phenylethynyl)furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(furan-3-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(oxazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(oxazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(oxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(isoxazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(isoxazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(isoxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(3-bromoisoxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(3-methoxyisoxazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(1,2,4-oxadiazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(1,2,4-oxadiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(1,3,4-oxadiazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(thiazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(thiazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(thiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(isothiazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(isothiazol-4-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(isothiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(1,2,4-thiadiazol-3-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(1,2,4-thiadiazol-5-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(1,3,4-thiadiazol-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   N-(pyridin-4-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,-   and pharmaceutically acceptable salts thereof.

One embodiment relates to compoundN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane, orpharmaceutically acceptable salts thereof. Another embodiment relates tocompound N-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane,or pharmaceutically acceptable salts thereof.

Compound Preparation

The compounds of the present invention can be prepared via the couplingof mono-protected diazabicycle (i.e., one in which one of the two aminefunctional groups is rendered un-reactive by suitable derivatization)with a suitably functionalized heteroaryl acid chloride or otherreactive carboxylic acid derivative.

There are numerous methods for preparing the mono-protecteddiazabicycles used to prepare the compounds of the present invention.Methods for the synthesis of a suitably protected3,7-diazabicyclo[3.3.0]octane are described in PCT WO 02/070523 toColon-Cruz et al. and in U.S. application 2006/0019985 to Zhenkun etal., in which N-benzylmaleimide is condensed with eitherparaformaldehyde and N-benzylglycine orN-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine to produce3,7-dibenzyl-3,7-diazabicyclo[3.3.0]octane-2,4-dione (also known as2,5-dibenzyltetrahydropyrrolo[3,4-c]pyrrole-1,3-dione). Subsequenttransformation of this intermediate can follow several paths. In oneinstance, treatment with α-chloroethylchloroformate produces3-benzyl-3,7-diazabicyclo[3.3.0]octane-2,4-dione (also known as2-benzyltetrahydropyrrolo[3,4-c]pyrrole-1,3-dione), which is thensequentially reduced (using borane-dimethylsulfide complex), convertedinto its N-(tert-butoxycarbonyl) derivative, and hydrogenated (to removethe second benzyl group). This producesN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane, which can be usedin coupling with carboxylic acids, and their derivatives, to producecompounds of the present invention. Alternately,3,7-dibenzyl-3,7-diazabicyclo[3.3.0]octane-2,4-dione can be reduced(with lithium aluminum hydride), partially hydrogenated (to remove onebenzyl group), converted into its N-(tert-butoxycarbonyl) derivative,and hydrogenated (to remove the second benzyl group), to produceN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane. Other methods forinstallation and removal of the benzyl, tert-butoxycarbonyl, and otheramine protecting groups are well known by those skilled in the art andare described further in T. W. Greene and P. G. M. Wuts, ProtectiveGroups in Organic Synthesis, 3^(rd) Edition, John Wiley & Sons, New York(1999).

An alternative preparation ofN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane has been describedin U.S. applications 2004/0186107 to Schrimpf et al. and 2005/0101602 toBasha et al., and involves the condensation of maleimide andN-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine to give7-benzyl-3,7-diazabicyclo[3.3.0]octane-2,4-dione (also known as5-benzyltetrahydropyrrolo[3,4-c]pyrrole-1,3-dione). Subsequent treatmentwith a reducing agent (e.g., lithium aluminum hydride) produces the3-benzyl-3,7-diazabicyclo[3.3.0]octane, the free amine of which can beprotected by a tert-butoxycabonyl group, followed by removal of thebenzyl protecting group by hydrogenolysis.

Maleate esters can be used as alternatives to maleimides in thesecondensation reactions. Thus, according to PCT WO 96/007656 to Schaus etal., condensation of N-benzylglycine with paraformaldehyde anddimethylmaleate will give N-benzyl-cis-3,4-pyrrolidinedicarboxylic aciddimethyl ester. This compound can then be reduced, for example, withlithium aluminum hydride, to give the diol, which can be further reactedwith methanesulfonyl chloride in the presence of triethylamine toproduce the corresponding dimesylate. Further treatment with ammonia andheat provides the N-benzyl protected 3,7-diazabicyclo[3.3.0]octane. Asdescribed above, this can be converted intoN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane.

Suitable derivatives of 3,7-diazabicyclo[3.3.1]nonane (bispidine) can beused to make compounds of the present invention. One such derivative isN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane, which can be madein a variety of ways. One synthesis proceeds throughN-benzyl-N′-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane,described by Stead et al. in Org. Lett. 7: 4459 (2005). Thus the Mannichreaction between N-(tert-butoxycarbonyl)piperidin-4-one, benzylamine andparaformaldehyde affordsN-benzyl-N′-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one,which can be treated sequentially with p-toluenesulfonhydrazide andsodium borohydride (to remove the carbonyl oxygen), givingN-benzyl-N′-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane. Thebenzyl group can be removed as described above to provideN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane. Alternativesyntheses of diazabicyclo[3.3.1]nonanes, suitable for conversion toeither N-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane or anothermono-protected derivative, have been described by Jeyaraman and Avila inChem. Rev. 81(2): 149-174 (1981) and in U.S. Pat. No. 5,468,858 toBerlin et al.

One means of making amides of the present invention is to couple theeither N-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane orN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane with a suitablyfunctionalized carboxylic acid and then remove the tert-butoxycarbonylprotecting group. Many such carboxylic acids are commercially available,and others can be easily prepared by procedures known to those skilledin the art. The condensation of an amine and a carboxylic acid, toproduce an amide, typically requires the use of a suitable activatingagent, such as N,N′-dicyclohexylcarbodiimide (DCC),(benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate(BOP), (benzotriazol-1-yloxy)tripyrrolidinophosphoniumhexafluorophosphate (PyBOP),O-(benzotriazol-1-yl)-N,N,N′,N′-bis(tetramethylene)uroniumhexafluorophosphate (HBPyU),O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate(HBTU), O-(benzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumtetrafluoroborate (TBTU), or(1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) (EDCI) with1-hydroxybenzotriazole (HOBt). Other activating agents are well known tothose skilled in the art (for example, see Kiso and Yajima, Peptides, pp39-91, Academic Press, San Diego, Calif. (1995)).

Alternatively, the amide bond can be formed by coupling a mono-protecteddiazabicycle with a suitably functionalized acid chloride, which may beavailable commercially or may be prepared by conversion of the suitablyfunctionalized carboxylic acid. The acid chloride may be prepared bytreatment of the appropriate carboxylic acid with, among other reagents,thionyl chloride or oxalyl chloride.

After amide formation, removal of the protecting group (e.g., thetert-butoxycarbonyl group) with acid, either aqueous or anhydrous, willafford the compounds of the present invention.

Those skilled in the art of organic synthesis will appreciate that thereexist multiple means of producing compounds of the present inventionwhich are labeled with a radioisotope appropriate to various diagnosticuses. Thus, condensation of a ¹¹C- or ¹⁸F-labeled heteroaromaticcarboxylic acid with eitherN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane orN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane, using the methodsdescribed above, and subsequent removal of the tert-butoxycarbonyl groupwill produce a compound suitable for use in positron emissiontomography.

Methods of Treatment

The compounds of the present invention are modulators of the α4β2 NNRsubtype, characteristic of the CNS, and can be used for preventingand/or treating various conditions or disorders, including those of theCNS, in subjects which have or are susceptible to such conditions ordisorders, by modulation of α4β2 NNRs. The compounds have the ability toselectively bind to the α4β2 NNRs and express nicotinic pharmacology(e.g., to act as agonists, partial agonists, antagonists and the like).For example, compounds of the present invention, when administered ineffective amounts to patients in need thereof, provide some degree ofprevention of the progression of the CNS disorder (i.e., providingprotective effects), amelioration of the symptoms of the CNS disorder,and/or amelioration of the reoccurrence of the CNS disorder.

The compounds of the present invention can be used to treat and/orprevent those types of conditions and disorders for which other types ofnicotinic compounds have been proposed as therapeutics. See, forexample, the references previously listed in the “Background of theInvention” section, as well as Williams et al., Drug News Perspec. 7(4):205 (1994), Arneric et al., CNS Drug Rev. 1(1): 1-26 (1995), Arneric etal., Exp. Opin. Invest. Drugs 5(1): 79-100 (1996), Bencherif et al., J.Pharmacol. Exp. Ther. 279: 1413 (1996), Lippiello et al., J. Pharmacol.Exp. Ther. 279: 1422 (1996), Damaj et al., J. Pharmacol. Exp. Ther. 291:390 (1999); Chiari et al., Anesthesiology 91: 1447 (1999), Lavand'hommeand Eisenbach, Anesthesiology 91: 1455 (1999), Holladay et al., J. Med.Chem. 40(28): 4169-94 (1997), Bannon et al., Science 279: 77 (1998), PCTWO 94/08992, PCT WO 96/31475, PCT WO 96/40682, and U.S. Pat. No.5,583,140 to Bencherif et al., U.S. Pat. No. 5,597,919 to Dull et al.,U.S. Pat. No. 5,604,231 to Smith et al. and U.S. Pat. No. 5,852,041 toCosford et al., the disclosures of which are incorporated herein byreference in their entirety.

The compounds and their pharmaceutical compositions are useful in thetreatment and/or prevention of a variety of CNS disorders, includingneurodegenerative disorders, neuropsychiatric disorders, neurologicdisorders, and addictions. The compounds and their pharmaceuticalcompositions can be used to treat and/or prevent cognitive deficits(age-related and otherwise), attentional disorders and dementias(including those due to infectious agents or metabolic disturbances); toprovide neuroprotection; to treat convulsions and multiple cerebralinfarcts; to treat mood disorders, compulsions and addictive behaviors;to provide analgesia; to control inflammation (such as mediated bycytokines and nuclear factor kappa B) and treat inflammatory disorders;to provide pain relief; and to treat infections (as anti-infectiousagents for treating bacterial, fungal and viral infections). Among thedisorders, diseases and conditions that the compounds and pharmaceuticalcompositions of the present invention can be used to treat and/orprevent are: age-associated memory impairment, mild cognitiveimpairment, pre-senile dementia (early onset Alzheimer's disease),senile dementia (dementia of the Alzheimer's type), Lewy body dementia,HIV-dementia, vascular dementia, Alzheimer's disease, stroke, AIDSdementia complex, attention deficit disorder, attention deficithyperactivity disorder, dyslexia, schizophrenia, schizophreniformdisorder, schizoaffective disorder, Parkinsonism including Parkinson'sdisease, Pick's disease, Huntington's chorea, tardive dyskinesia,hyperkinesia, progressive supranuclear palsy, Creutzfeld-Jakob disease,multiple sclerosis, amyotrophic lateral sclerosis, epilepsy, mania,anxiety, depression, panic disorders, bipolar disorders, generalizedanxiety disorder, obsessive compulsive disorder, rage outbursts,Tourette's syndrome, autism, drug and alcohol addiction, tobaccoaddiction, obesity, cachexia, psoriasis, lupus, acute cholangitis,aphthous stomatitis, asthma, ulcerative colitis, inflammatory boweldisease, pouchitis, viral pneumonitis and arthritis (e.g., rheumatoidarthritis and osteoarthritis), endotoxaemia, sepsis, atherosclerosis,idiopathic pulmonary fibrosis and neoplasias.

It is advantageous that the treatment or prevention of diseases,disorders and conditions occurs without appreciable adverse side effects(e.g., significant increases in blood pressure and heart rate,significant negative effects upon the gastro-intestinal tract, andsignificant effects upon skeletal muscle). The compounds of the presentinvention, when employed in effective amounts, can modulate the activityof the α4β2 NNRs without appreciable interaction with the nicotinicsubtypes that characterize the human ganglia (as demonstrated by theirlack of the ability of to elicit nicotinic function in adrenalchromaffin tissue) or skeletal muscle (as demonstrated by their lack ofability to elicit nicotinic function in cell preparations expressingmuscle-type nicotinic receptors). Thus, these compounds are capable oftreating and/or preventing diseases, disorders and conditions withouteliciting significant side effects associated activity at ganglionic andneuromuscular sites. Thus, administration of the compounds provides atherapeutic window in which treatment of certain diseases, disorders andconditions is provided, and certain side effects are avoided. That is,an effective dose of the compound is sufficient to provide the desiredeffects upon the disease, disorder or condition, but is insufficient(i.e., is not at a high enough level) to provide undesirable sideeffects.

Thus, the present invention provides the use of a compound or Formula I,or a pharmaceutically acceptable salt thereof, for use in therapy (suchas a therapy described above).

In yet another aspect the present invention provides the use of acompound or Formula I, or a pharmaceutically acceptable salt thereof, inthe manufacture of a medicament for use in the treatment of a CNSdisorder (such as a disorder, disease or condition described above).

In a further aspect the invention provides the use of a compound ofFormula I, or a pharmaceutically acceptable salt thereof, in themanufacture of a medicament for use in the treatment mild to moderatedementia of the Alzheimer's type, attention deficit disorder, mildcognitive impairment and age associated memory impairment.

Diagnostic Uses

The compounds can be used in diagnostic compositions, such as probes,particularly when they are modified to include appropriate labels. Theprobes can be used, for example, to determine the relative number and/orfunction of specific receptors, particularly the α4β2 receptor subtype.For this purpose the compounds of the present invention most preferablyare labeled with a radioactive isotopic moiety such as ¹¹C, ¹⁸F, ⁷⁶Br,¹²³I or ¹²⁵I.

The administered compounds can be detected using known detection methodsappropriate for the label used. Examples of detection methods includeposition emission topography (PET) and single-photon emission computedtomography (SPECT). The radiolabels described above are useful in PET(e.g., ¹¹C, ¹⁸F, or ⁷⁶Br) and SPECT (e.g., ¹²³I) imaging, withhalf-lives of about 20.4 minutes for ¹¹C, about 109 minutes for ¹⁸F,about 13 hours for ¹²³I, and about 16 hours for ⁷⁶Br. A high specificactivity is desired to visualize the selected receptor subtypes atnon-saturating concentrations. The administered doses typically arebelow the toxic range and provide high contrast images. The compoundsare expected to be capable of administration in non-toxic levels.Determination of dose is carried out in a manner known to one skilled inthe art of radiolabel imaging. See, for example, U.S. Pat. No. 5,969,144to London et al.

The compounds can be administered using known techniques. See, forexample, U.S. Pat. No. 5,969,144 to London et al. The compounds can beadministered in formulation compositions that incorporate otheringredients, such as those types of ingredients that are useful informulating a diagnostic composition. Compounds useful in accordancewith carrying out the present invention most preferably are employed informs of high purity. See, U.S. Pat. No. 5,853,696 to Elmalch et al.

After the compounds are administered to a subject (e.g., a humansubject), the presence of that compound within the subject can be imagedand quantified by appropriate techniques in order to indicate thepresence, quantity, and functionality of selected NNR subtypes. Inaddition to humans, the compounds can also be administered to animals,such as mice, rats, dogs, and monkeys. SPECT and PET imaging can becarried out using any appropriate technique and apparatus. SeeVillemagne et al., In: Arneric et al. (Eds.) Neuronal NicotinicReceptors: Pharmacology and Therapeutic Opportunities, 235-250 (1998)and U.S. Pat. No. 5,853,696 to Elmalch et al. for a disclosure ofrepresentative imaging techniques.

The radiolabeled compounds bind with high affinity to selective NNRsubtypes (e.g., α4β2) and preferably exhibit negligible non-specificbinding to other nicotinic cholinergic receptor subtypes (e.g., thosereceptor subtypes associated with muscle and ganglia). As such, thecompounds can be used as agents for noninvasive imaging of nicotiniccholinergic receptor subtypes within the body of a subject, particularlywithin the brain for diagnosis associated with a variety of CNS diseasesand disorders.

In one aspect, the diagnostic compositions can be used in a method todiagnose disease in a subject, such as a human patient. The methodinvolves administering to that patient a detectably labeled compound asdescribed herein, and detecting the binding of that compound to selectedNNR subtypes (e.g., α4β2 receptor subtype). Those skilled in the art ofusing diagnostic tools, such as PET and SPECT, can use the radiolabeledcompounds described herein to diagnose a wide variety of conditions anddisorders, including conditions and disorders associated withdysfunction of the central and autonomic nervous systems. Such disordersinclude a wide variety of CNS diseases and disorders, includingAlzheimer's disease, Parkinson's disease, and schizophrenia. These andother representative diseases and disorders that can be evaluatedinclude those that are set forth in U.S. Pat. No. 5,952,339 to Bencherifet al.

In another aspect, the diagnostic compositions can be used in a methodto monitor selective nicotinic receptor subtypes of a subject, such as ahuman patient. The method involves administering a detectably labeledcompound as described herein to that patient and detecting the bindingof that compound to selected nicotinic receptor subtypes (e.g., the α4β2receptor subtype).

Pharmaceutical Compositions

According to one embodiment of the present invention there is provided apharmaceutical composition comprising as active ingredient atherapeutically effective amount of a compound of the present invention,in association with one or more pharmaceutically acceptable diluents,excipients and/or inert carriers.

The manner in which the compounds are administered can vary. Thecompositions are preferably administered orally (e.g., in liquid formwithin a solvent such as an aqueous or non-aqueous liquid, or within asolid carrier). Preferred compositions for oral administration includepills, tablets, capsules, caplets, syrups, and solutions, including hardgelatin capsules and time-release capsules. Compositions may beformulated in unit dose form, or in multiple or subunit doses. Preferredcompositions are in liquid or semisolid form. Compositions including aliquid pharmaceutically inert carrier such as water or otherpharmaceutically compatible liquids or semisolids may be used. The useof such liquids and semisolids is well known to those of skill in theart.

The compositions can also be administered via injection, i.e.,intravenously, intramuscularly, subcutaneously, intraperitoneally,intraarterially, intrathecally, and intracerebroventricularly.Intravenous administration is a preferred method of injection. Suitablecarriers for injection are well known to those of skill in the art, andinclude 5% dextrose solutions, saline, and phosphate buffered saline.The compounds can also be administered as an infusion or injection(e.g., as a suspension or as an emulsion in a pharmaceuticallyacceptable liquid or mixture of liquids).

The formulations may also be administered using other means, forexample, rectal administration. Formulations useful for rectaladministration, such as suppositories, are well known to those of skillin the art. The compounds can also be administered by inhalation (e.g.,in the form of an aerosol either nasally or using delivery articles ofthe type set forth in U.S. Pat. No. 4,922,901 to Brooks et al., thedisclosure of which is incorporated herein in its entirety); topically(e.g., in lotion form); transdermally (e.g., using a transdermal patch,using technology that is commercially available from Novartis and AlzaCorporation, or by powder injection); or by buccal, sublingual orintranasal absorption. Although it is possible to administer thecompounds in the form of a bulk active chemical, it is preferred topresent each compound in the form of a pharmaceutical composition orformulation for efficient and effective administration.

Exemplary methods for administering such compounds will be apparent tothe skilled artisan. The usefulness of these formulations may depend onthe particular composition used and the particular subject receiving thetreatment. For example, the compositions can be administered in the formof a tablet, a hard gelatin capsule or as a time release capsule. Theseformulations may contain a liquid carrier that may be oily, aqueous,emulsified or contain certain solvents suitable to the mode ofadministration.

The administration of the pharmaceutical compositions described hereincan be intermittent, or at a gradual, continuous, constant or controlledrate to a warm-blooded animal, (e.g., a mammal such as a mouse, rat,cat, rabbit, dog, pig, cow, or monkey); but advantageously is preferablyadministered to a human being. In addition, the time of day and thenumber of times per day that the pharmaceutical composition isadministered can vary.

The appropriate dose of the compound is that amount effective to preventoccurrence of the symptoms of the disorder or to treat some symptoms ofthe disorder from which the patient suffers. By “effective amount”,“therapeutic amount” or “effective dose” is meant that amount sufficientto elicit the desired pharmacological or therapeutic effects, thusresulting in effective prevention or treatment of the disorder. Thus,when treating a CNS disorder, an effective amount of compound is anamount sufficient to pass across the blood-brain barrier of the subject,to bind to relevant receptor sites in the brain of the subject, and tomodulate the activity of relevant nicotinic receptor subtypes (e.g.,modulate neurotransmitter secretion, thus resulting in effectiveprevention or treatment of the disorder). Prevention of the disorder ismanifested by delaying the onset of the symptoms of the disorder.Treatment of the disorder is manifested by a decrease in the symptomsassociated with the disorder or an amelioration of the reoccurrence ofthe symptoms of the disorder.

The effective dose can vary, depending upon factors such as thecondition of the patient, the severity of the symptoms of the disorder,and the manner in which the pharmaceutical composition is administered.For human patients, the effective dose of typical compounds generallyrequires administering the compound in an amount sufficient to modulatedisease-relevant receptors to affect neurotransmitter (e.g., dopamine)release but the amount should be insufficient to induce effects onskeletal muscles and ganglia to any significant degree. The effectivedose of compounds will of course differ from patient to patient but ingeneral includes amounts starting where CNS effects or other desiredtherapeutic effects occur, but below the amount where muscular andganglionic effects are observed.

Typically, to be administered in an effective dose, compounds requireadministering in an amount of less than 5 mg/kg of patient weight.Often, the compounds may be administered in an amount from less thanabout 1 mg/kg patient weight to less than about 100 μg/kg of patientweight, and occasionally between about 10 μg/kg to less than 100 μg/kgof patient weight. The foregoing effective doses typically representthat amount administered as a single dose, or as one or more dosesadministered over a 24 hours period. For human patients, the effectivedose of the compounds may require administering the compound in anamount of at least about 1, but not more than about 1000, and often notmore than about 500 mg/24 hr/patient.

Compositions useful as diagnostics can be employed, as set forth in U.S.Pat. No. 5,853,696 to Elmalch et al. and U.S. Pat. No. 5,969,144 toLondon et al., the contents of which are hereby incorporated byreference. The compounds also can be administered in formulationcompositions that incorporate other ingredients, such as those types ofingredients that are useful in formulating a diagnostic composition.

The following examples are provided to illustrate the present invention,and should not be construed as limiting thereof. In these examples, allparts and percentages are by weight, unless otherwise noted.

Biological Assays EXAMPLE 1 Radioligand Binding at CNS nAChRs

α4β2 nAChR Subtype

Preparation of Membranes from Rat Cortex:

Rats (female, Sprague-Dawley), weighing 150-250 g, were maintained on a12 h light/dark cycle and were allowed free access to water and foodsupplied by PMI Nutrition International, Inc. Animals were anesthetizedwith 70% CO₂, and then decapitated. Brains were removed and placed on anice-cold platform. The cerebral cortex was removed and placed in 20volumes (weight:volume) of ice-cold preparative buffer (137 mM NaCl,10.7 mM KCl, 5.8 mM KH₂PO₄, 8 mM Na₂HPO₄, 20 mM HEPES (free acid), 5 mMiodoacetamide, 1.6 mM EDTA, pH 7.4); PMSF, dissolved in methanol to afinal concentration of 100 μM, was added and the suspension washomogenized by Polytron. The homogenate was centrifuged at 18,000×g for20 min at 4° C. and the resulting pellet was re-suspended in 20 volumesof ice-cold water. After 60 min incubation on ice, a new pellet wascollected by centrifugation at 18,000×g for 20 min at 4° C. The finalpellet was re-suspended in 10 volumes of buffer and stored at −20° C.

Preparation of Membranes from SH-EP1/Human α4β2 Clonal Cells:

Cell pellets from 40 150 mm culture dishes were pooled, and homogenizedby Polytron (Kinematica GmbH, Switzerland) in 20 milliliters of ice-coldpreparative buffer. The homogenate was centrifuged at 48,000 g for 20minutes at 4° C. The resulting pellet was re-suspended in 20 mL ofice-cold preparative buffer and stored at −20° C.

On the day of the assay, the frozen membranes were thawed and spun at48,000×g for 20 min. The supernatant was decanted and discarded. Thepellet was resuspended in Dulbecco's phosphate buffered saline (PBS,Life Technologies) pH 7.4 and homogenized with the Polytron for 6seconds. Protein concentrations were determined using a Pierce BCAProtein Assay Kit, with bovine serum albumin as the standard (PierceChemical Company, Rockford, Ill.).

Membrane preparations (approximately 50 μg for human and 200-300 μgprotein for rat α4β2) were incubated in PBS (50 μL and 100 μLrespectively) in the presence of competitor compound (0.01 nM to 100 μM)and 5 nM [³H]nicotine for 2-3 hours on ice. Incubation was terminated byrapid filtration on a multi-manifold tissue harvester (Brandel,Gaithersburg, Md.) using GF/B filters presoaked in 0.33%polyethyleneimine (w/v) to reduce non-specific binding. Tissue wasrinsed 3 times in PBS, pH 7.4. Scintillation fluid was added to filterscontaining the washed tissue and allowed to equilibrate. Filters werethen counted to determine radioactivity bound to the membranes by liquidscintillation counting (2200CA Tri-Carb LSC, Packard Instruments, 50%efficiency or Wallac Trilux 1450 MicroBeta, 40% efficiency, PerkinElmer).

Data were expressed as disintegrations per minute (DPMs). Within eachassay, each point had 2-3 replicates. The replicates for each point wereaveraged and plotted against the log of the drug concentration. IC₅₀,which is the concentration of the compound that produces 50% inhibitionof binding, was determined by least squares non-linear regression. Kivalues were calculated using the Cheng-Prussof equation (1973):Ki=IC ₅₀/(1+N/Kd)where N is the concentration of [³H]nicotine and Kd is the affinity ofnicotine (3 nM, determined in a separate experiment).

α7 nAChR Subtype

Rats (female, Sprague-Dawley), weighing 150-250 g, were maintained on a12 h light/dark cycle and were allowed free access to water and foodsupplied by PMI Nutrition International, Inc. Animals were anesthetizedwith 70% CO₂, then decapitated. Brains were removed and placed on anice-cold platform. The hippocampus was removed and placed in 10 volumes(weight:volume) of ice-cold preparative buffer (137 mM NaCl, 10.7 mMKCl, 5.8 mM KH₂PO₄, 8 mM Na₂HPO₄, 20 mM HEPES (free acid), 5 mMiodoacetamide, 1.6 mM EDTA, pH 7.4); PMSF, dissolved in methanol to afinal concentration of 100 μM, was added and the tissue suspension washomogenized by Polytron. The homogenate was centrifuged at 18,000×g for20 min at 4° C. and the resulting pellet was re-suspended in 10 volumesof ice-cold water. After 60 min incubation on ice, a new pellet wascollected by centrifugation at 18,000×g for 20 min at 4° C. The finalpellet was re-suspended in 10 volumes of buffer and stored at −20° C. Onthe day of the assay, tissue was thawed, centrifuged at 18,000×g for 20min, and then re-suspended in ice-cold PBS (Dulbecco's PhosphateBuffered Saline, 138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1 mMNa₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH 7.4) to afinal concentration of approximately 2 mg protein/mL. Protein wasdetermined by the method of Lowry et al., J. Biol. Chem. 193: 265(1951), using bovine serum albumin as the standard.

The binding of [³H]MLA was measured using a modification of the methodsof Davies et al., Neuropharmacol. 38: 679 (1999). [³H]MLA (SpecificActivity=25-35 Ci/mmol) was obtained from Tocris. The binding of [³H]MLAwas determined using a 2 h incubation at 21° C. Incubations wereconducted in 48-well micro-titre plates and contained about 200 μg ofprotein per well in a final incubation volume of 300 μL. The incubationbuffer was PBS and the final concentration of [³H]MLA was 5 nM. Thebinding reaction was terminated by filtration of the protein containingbound ligand onto glass fiber filters (GF/B, Brandel) using a BrandelTissue Harvester at room temperature. Filters were soaked in de-ionizedwater containing 0.33% polyethyleneimine to reduce non-specific binding.Each filter was washed with PBS (3×1 mL) at room temperature.Non-specific binding was determined by inclusion of 50 μMnon-radioactive MLA in selected wells.

The inhibition of [³H]MLA binding by test compounds was determined byincluding seven different concentrations of the test compound inselected wells. Each concentration was replicated in triplicate. IC₅₀values were estimated as the concentration of compound that inhibited 50percent of specific [³H]MLA binding. Inhibition constants (Ki values),reported in nM, were calculated from the IC₅₀ values using the method ofCheng et al., Biochem. Pharmacol. 22: 3099-3108 (1973).

EXAMPLE 2 Determination of Dopamine Release

Dopamine release was measured using striatal synaptosomes obtained fromrat brain, according to the procedures set forth by Rapier et al., J.Neurochem. 54: 937 (1990). Rats (female, Sprague-Dawley), weighing150-250 g, were maintained on a 12 h light/dark cycle and were allowedfree access to water and food supplied by PMI Nutrition International,Inc. Animals were anesthetized with 70% CO₂, then decapitated. Thebrains were quickly removed and the striata dissected. Striatal tissuefrom each of 2 rats was pooled and homogenized in ice-cold 0.32 Msucrose (5 mL) containing 5 mM HEPES, pH 7.4, using a glass/glasshomogenizer. The tissue was then centrifuged at 1,000×g for 10 min. Thepellet was discarded and the supernatant was centrifuged at 12,000×g for20 min. The resulting pellet was re-suspended in perfusion buffercontaining monoamine oxidase inhibitors (128 mM NaCl, 1.2 mM KH₂PO₄, 2.4mM KCl, 3.2 mM CaCl₂, 1.2 mM MgSO₄, 25 mM HEPES, 1 mM ascorbic acid,0.02 mM pargyline HCl and 10 mM glucose, pH 7.4) and centrifuged for 15min at 25,000×g. The final pellet was resuspended in perfusion buffer(1.4 mL) for immediate use.

The synaptosomal suspension was incubated for 10 min at 37° C. torestore metabolic activity. [³H]Dopamine ([³H]DA, specific activity=28.0Ci/mmol, NEN Research Products) was added at a final concentration of0.1 μM and the suspension was incubated at 37° C. for another 10 min.Aliquots of tissue (50 μL) and perfusion buffer (100 μL) were loadedinto the suprafusion chambers of a Brandel Suprafusion System (series2500, Gaithersburg, Md.). Perfusion buffer (room temperature) was pumpedinto the chambers at a rate of 1.5 mL/min for a wash period of 16 min.Test compound (10 μM) or nicotine (10 μM) was then applied in theperfusion stream for 48 sec. Fractions (24 sec each) were continuouslycollected from each chamber throughout the experiment to capture basalrelease and agonist-induced peak release and to re-establish thebaseline after the agonist application. The perfusate was collecteddirectly into scintillation vials, to which scintillation fluid wasadded. [³H]DA released was quantified by scintillation counting. Foreach chamber, the integrated area of the peak was normalized to itsbaseline.

Release was expressed as a percentage of release obtained with an equalconcentration of L-nicotine. Within each assay, each test compound wasreplicated using 2-3 chambers; replicates were averaged. Whenappropriate, dose-response curves of test compound were determined. Themaximal activation for individual compounds (Emax) was determined as apercentage of the maximal activation induced by L-nicotine. The compoundconcentration resulting in half maximal activation (EC₅₀) of specificion flux was also defined.

EXAMPLE 3 Selectivity vs. Peripheral nAChRs

Interaction at the Human Muscle nAChR Subtype

Activation of muscle-type nAChRs was established on the human clonalline TE671/RD, which is derived from an embryonal rhabdomyosarcoma(Stratton et al., Carcinogen 10: 899 (1989)). These cells expressreceptors that have pharmacological (Lukas, J. Pharmacol. Exp. Ther.251: 175 (1989)), electrophysiological (Oswald et al., Neurosci. Lett.96: 207 (1989)), and molecular biological profiles (Luther et al., J.Neurosci. 9: 1082 (1989)) similar to the muscle-type nAChR.

TE671/RD cells were maintained in proliferative growth phase accordingto routine protocols (Bencherif et al., Mol. Cell. Neurosci. 2: 52(1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946 (1991)).Cells were cultured in Dulbecco's modified Eagle's medium (Gibco/BRL)with 10% horse serum (Gibco/BRL), 5% fetal bovine serum (HyClone, LoganUtah), 1 mM sodium pyruvate, 4 mM L-Glutamine, and 50,000 unitspenicillin-streptomycin (Irvine Scientific). When cells were 80%confluent, they were plated to 12 well polystyrene plates (Costar).Experiments were conducted when the cells reached 100% confluency.

Nicotinic acetylcholine receptor (nAChR) function was assayed using⁸⁶Rb⁺ efflux according to the method described by Lukas et al., Anal.Biochem. 175: 212 (1988). On the day of the experiment, growth media wasgently removed from the well and growth media containing ⁸⁶Rubidiumchloride (10⁶ μCi/mL) was added to each well. Cells were incubated at37° C. for a minimum of 3 h. After the loading period, excess ⁸⁶Rb⁺ wasremoved and the cells were washed twice with label-free Dulbecco'sphosphate buffered saline (138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH. 7.4),taking care not to disturb the cells. Next, cells were exposed to either100 μM of test compound, 100 μM of L-nicotine (Acros Organics) or bufferalone for 4 min. Following the exposure period, the supernatantcontaining the released ⁸⁶Rb⁺ was removed and transferred toscintillation vials. Scintillation fluid was added and releasedradioactivity was measured by liquid scintillation counting.

Within each assay, each point had 2 replicates, which were averaged. Theamount of ⁸⁶Rb⁺ release was compared to both a positive control (100 μML-nicotine) and a negative control (buffer alone) to determine thepercent release relative to that of L-nicotine.

When appropriate, dose-response curves of test compound were determined.The maximal activation for individual compounds (Emax) was determined asa percentage of the maximal activation induced by L-nicotine. Thecompound concentration resulting in half maximal activation (EC₅₀) ofspecific ion flux was also determined

Interaction at the Rat Ganglionic nAChR Subtype

Activation of rat ganglion nAChRs was established on thepheochromocytoma clonal line PC12, which is a continuous clonal cellline of neural crest origin, derived from a tumor of the rat adrenalmedulla. These cells express ganglion-like nAChR s (see Whiting et al.,Nature 327: 515 (1987); Lukas, J. Pharmacol. Exp. Ther. 251: 175 (1989);Whiting et al., Mol. Brain Res. 10: 61 (1990)).

Rat PC12 cells were maintained in proliferative growth phase accordingto routine protocols (Bencherif et al., Mol. Cell. Neurosci. 2: 52(1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946 (1991)).Cells were cultured in Dulbecco's modified Eagle's medium (Gibco/BRL)with 10% horse serum (Gibco/BRL), 5% fetal bovine serum (HyClone, LoganUtah), 1 mM sodium pyruvate, 4 mM L-Glutamine, and 50,000 unitspenicillin-streptomycin (Irvine Scientific). When cells were 80%confluent, they were plated to 12 well Nunc plates (Nunclon) and coatedwith 0.03% poly-L-lysine (Sigma, dissolved in 100 mM boric acid).Experiments were conducted when the cells reached 80% confluency.

Nicotinic acetylcholine receptor (nAChR) function was assayed using⁸⁶Rb⁺ efflux according to a method described by Lukas et al., Anal.Biochem. 175: 212 (1988). On the day of the experiment, growth media wasgently removed from the well and growth media containing ⁸⁶Rubidiumchloride (10⁶ μCi/mL) was added to each well. Cells were incubated at37° C. for a minimum of 3 h. After the loading period, excess ⁸⁶Rb⁺ wasremoved and the cells were washed twice with label-free Dulbecco'sphosphate buffered saline (138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH. 7.4),taking care not to disturb the cells. Next, cells were exposed to either100 μM of test compound, 100 μM of nicotine or buffer alone for 4 min.Following the exposure period, the supernatant containing the released⁸⁶Rb⁺ was removed and transferred to scintillation vials. Scintillationfluid was added and released radioactivity was measured by liquidscintillation counting

Within each assay, each point had 2 replicates, which were averaged. Theamount of ⁸⁶Rb⁻ release was compared to both a positive control (100 μMnicotine) and a negative control (buffer alone) to determine the percentrelease relative to that of L-nicotine.

When appropriate, dose-response curves of test compound were determined.The maximal activation for individual compounds (Emax) was determined asa percentage of the maximal activation induced by L-nicotine. Thecompound concentration resulting in half maximal activation (EC₅₀) ofspecific ion flux was also determined.

Interaction at the Human Ganglionic nAChR Subtype

The cell line SH—SY5Y is a continuous line derived by sequentialsubcloning of the parental cell line, SK—N—SH, which was originallyobtained from a human peripheral neuroblastoma. SH—SY5Y cells express aganglion-like nAChR (Lukas et al., Mol. Cell. Neurosci. 4: 1 (1993)).

Human SH—SY5Y cells were maintained in proliferative growth phaseaccording to routine protocols (Bencherif et al., Mol. Cell. Neurosci.2: 52 (1991) and Bencherif et al., J. Pharmacol. Exp. Ther. 257: 946(1991)). Cells were cultured in Dulbecco's modified Eagle's medium(Gibco/BRL) with 10% horse serum (Gibco/BRL), 5% fetal bovine serum(HyClone, Logan Utah), 1 mM sodium pyruvate, 4 mM L-Glutamine, and50,000 units penicillin-streptomycin (Irvine Scientific). When cellswere 80% confluent, they were plated to 12 well polystyrene plates(Costar). Experiments were conducted when the cells reached 100%confluency.

Nicotinic acetylcholine receptor (nAChR) function was assayed using⁸⁶Rb⁺ efflux according to a method described by Lukas et al., Anal.Biochem. 175: 212 (1988). On the day of the experiment, growth media wasgently removed from the well and growth media containing ⁸⁶Rubidiumchloride (10⁶ μCi/mL) was added to each well. Cells were incubated at37° C. for a minimum of 3 h. After the loading period, excess ⁸⁶Rb⁺ wasremoved and the cells were washed twice with label-free Dulbecco'sphosphate buffered saline (138 mM NaCl, 2.67 mM KCl, 1.47 mM KH₂PO₄, 8.1mM Na₂HPO₄, 0.9 mM CaCl₂, 0.5 mM MgCl₂, Invitrogen/Gibco, pH 7.4),taking care not to disturb the cells. Next, cells were exposed to either100 μM of test compound, 100 μM of nicotine, or buffer alone for 4 min.Following the exposure period, the supernatant containing the released⁸⁶Rb⁺ was removed and transferred to scintillation vials. Scintillationfluid was added and released radioactivity was measured by liquidscintillation counting

Within each assay, each point had 2 replicates, which were averaged. Theamount of ⁸⁶Rb⁺ release was compared to both a positive control (100 μMnicotine) and a negative control (buffer alone) to determine the percentrelease relative to that of L-nicotine.

When appropriate, dose-response curves of test compound were determined.The maximal activation for individual compounds (Emax) was determined asa percentage of the maximal activation induced by L-nicotine. Thecompound concentration resulting in half maximal activation (EC₅₀) ofspecific ion flux was also defined.

EXAMPLE 4 Novel Object Recognition (NOR) Task

The novel object recognition (NOR) task was performed in accord with thedescription of Ennaceur and Delacour Behav. Brain Res. 100: 85-92(1988).

SYNTHETIC EXAMPLES EXAMPLE 5 Synthesis ofN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane

Example 5 relates to the synthesis ofN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane, which wasprepared as described in U.S. applications 2004/0186107 to Schrimpf etal. and 2005/0101602 to Basha et al., according to the followingtechniques:

5-Benzyltetrahydropyrrolo[3,4-c]pyrrole-1,3-dione (or7-benzyl-3,7-diazabicyclo[3.3.0]octan-2,4-dione)

Trifluoroacetic acid (TFA, 0.50 mL, 6.5 mmol) was added to a cold (0°C.) solution of maleimide (6.27 g, 0.0646 mol) in dichloromethane (150mL) under nitrogen. A solution ofN-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine (20 g, 0.084 mol)in dichloromethane (100 mL) was added drop-wise over 45 min. After theaddition was complete, the mixture was warmed slowly to ambienttemperature and stirred for 16 h. The mixture was concentrated and theresulting residue was dissolved in dichloromethane (200 mL) and washedwith saturated aqueous sodium bicarbonate (2×50 mL). The aqueous layerwas separated and extracted with dichloromethane (2×75 mL). The combineddichloromethane extracts were washed with brine (50 mL), dried overanhydrous magnesium sulfate, filtered and concentrated to give 12.5 g(83.9% yield) of a light yellow, waxy solid (MS m/z 231 (M+H)).

2-Benzyloctahydropyrrolo[3,4-c]pyrrole (or3-benzyl-3,7-diazabicyclo[3.3.0]octane)

The crude 5-benzyltetrahydropyrrolo[3,4-c]pyrrole-1,3-dione (4.9 g,0.021 mol) was dissolved in cold (0° C.) dry tetrahydrofuran (THF) (50mL) under nitrogen, and lithium aluminum hydride (63 mL of 1 M in THF,0.063 mol) was added drop-wise over 30 min to the continuously cooledsolution. The resulting mixture was stirred at ambient temperature for30 min and then warmed to reflux for 4 h. The mixture was then cooled to0° C. and quenched by the slow addition of excess solid sodium sulfatedecahydrate. The mixture was warmed to ambient temperature and stirredfor 16 h. The solids were filtered and the residue was washed with ethylacetate (3×100 mL). The combined filtrates were concentrated to give 4.2g (99% yield) of a waxy solid (MS m/z 203 (M+H)).

5-Benzylhexahydropyrrolo[3,4-c]pyrrole-2-carboxylic acid tert-butylester (orN-benzyl-N′-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane)

The crude 2-benzyloctahydropyrrolo[3,4-c]pyrrole (4.2 g, 0.021 mol) wasdissolved in THF (50 mL). Di-t-butyl dicarbonate (5.5 g, 0.025 mol) andaqueous saturated NaHCO₃ (10 mL) were added, and the mixture was stirredat ambient temperature overnight. The reaction was quenched with water(10 mL), and ethyl acetate (30 mL) was added. The aqueous layer wasextracted with ethyl acetate (2×20 mL), and the combined organicextracts were dried over anhydrous sodium sulfate and concentrated.Purification via silica gel column chromatography (1:1 hexanes/ethylacetate) gave 5.07 g (79.8% yield) of the title compound (MS m/z 303(M+H)).

Hexahydropyrrolo[3,4-c]pyrrole-2-carboxylic acid tert-butyl ester (orN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.0]octane)

The 5-benzylhexahydropyrrolo[3,4-c]pyrrole-2-carboxylic acid tert-butylester (5.07 g, 0.0168 mol) was dissolved in methanol (50 mL) and 20%Pd(OH)₂/C (wet) (˜2 g) was added under a nitrogen atmosphere. Theresulting mixture was warmed (45-50° C.) and shaken for 2 h under 40 psiof hydrogen. The mixture was filtered and concentrated to give 3.49 g(97.7% yield) of the title compound (MS m/z 213 (M+H)).

EXAMPLE 6 Synthesis ofN-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane

Example 6 relates to the synthesis offuran-2-yl(hexahydropyrrolo[3,4-c]pyrrol-2-yl)methanone (orN-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane), which wasprepared according to the following techniques, illustrative of thecoupling reaction used to make heteroaromatic amides of3,7-diazabicyclo[3.3.0]octane:

Furan-2-yl(hexahydropyrrolo[3,4-c]pyrrol-2-yl)methanone trifluoroacetate(or N-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octanetrifluoroacetate)

Furan-2-carboxylic acid (0.037 g, 0.33 mmol) and triethylamine (0.125mL, 0.99 mmol) were combined in dry dichloromethane (1 mL), andO-(benzotriazol-1-yl)-1,1,3,3,-tetramethyluronium hexafluorophosphate(HBTU; 0.125 g, 0.33 mmol) was added. A solution ofhexahydropyrrolo[3,4-c]pyrrole-2-carboxylic acid tert-butyl ester (0.064g, 0.30 mmol) in dichloromethane (0.5 mL) was added, and the mixture wasstirred at ambient temperature overnight. The mixture was shaken with10% aqueous sodium hydroxide, and the organic layer was separated. Theaqueous layer was extracted with chloroform (2×2 mL). The combinedorganic extracts were washed with water (2×1 mL) and concentrated. Theresulting residue was dissolved in dimethylformamide (DMF) (0.3 mL) andpurified by HPLC (acetonitrile/water gradient). Fractions containing thedesired material were pooled and concentrated, leaving thetert-butoxycarbonyl-protected product. This material was dissolved in amixture of trifluoroacetic acid (0.5 mL) and dichloromethane (0.5 mL),and the mixture was stirred at ambient temperature for 1 h. Thevolatiles were removed by rotary evaporation, followed by high vacuumtreatment, to give 77 mg of an oil (80% yield) (¹H NMR (d₄-methanol, 300MHz) 3.20 (m, 2H), 3.47-4.2 (m, 8H), 6.60 (t, 1H), 7.18 (d, 1H), 7.72(d, 1H); MS m/z 207 (M+H)).

EXAMPLE 7 Synthesis ofN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octanetrifluoroacetate

Example 7 relates to the synthesis of5-chlorofuran-2-yl(hexahydropyrrolo[3,4-c]pyrrol-2-yl)methanonetrifluoroacetate (orN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octanetrofluoroacetate), which was prepared according to the followingtechniques, illustrative of the coupling reaction used to makeheteroaromatic amides of 3,7-diazabicyclo[3.3.0]octane:

5-Chlorofuran-2-carboxylic acid

Aqueous sodium hydroxide (80 mL of 10%) was added to a solution ofsilver nitrate (8.0 g, 47 mmol) in water (20 mL). This suspension wasstirred and slowly treated with 30% aqueous ammonium hydroxide until itbecame clear. A solution of 5-chlorofuran-2-carboxaldehyde (3.0 g, 23mmol) (Aldrich Chemical) in methanol (5 mL) was added, and the resultingmixture was stirred at ambient temperature for 30 min. The reactionmixture was filtered, and the filtrate was washed with ether (100 mL).The aqueous filtrate was then made acidic (˜pH 3) by the addition ofcold 20% sulfuric acid. The resulting mixture was extracted with ethylacetate (3×100 mL). The extracts were washed with saturated aqueoussodium chloride solution (100 mL), dried (anhydrous sodium sulfate) andconcentrated under vacuum to give 3.2 g (95% yield) of white solid (mp178-179° C.). This reaction was easily scalable and was run multipletimes at >10 g scale.

N-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octanetrifluoroacetate

Oxalyl chloride (12.2 g, 95.8 mmol) containing a drop of DMF was addeddrop-wise to an ice-cooled solution of 5-chlorofuran-2-carboxylic acid(6.25 g, 47.9 mmol) in 200 mL of dichloromethane. After completeaddition, the ice bath was removed and the reaction was warmed toambient temperature over a 1 h period. The volatiles were then removedunder vacuum, and the residue was dissolved in THF (50 mL). Thissolution of the acid chloride was then added to an stirred, ice-cooledsolution of hexahydropyrrolo[3,4-c]pyrrole-2-carboxylic acid tert-butylester (10.2 g, 47.9 mmol) and diisopropylethylamine (25 g, ˜4equivalents) in THF (200 mL). This mixture was stirred at ambienttemperature for 16 h. The volatiles were then removed under vacuum, andthe residue was partitioned between water (100 mL) and ether (300 mL).The ether layer and two ether extracts (100 mL) of the aqueous layerwere concentrated on the rotary evaporator. The residue was columnchromatographed on silica gel, eluting with a 0-60% ethyl acetate inhexane gradient. Concentration of selected fractions gave 13.9 g (85.3%yield) of pale yellow syrup. A portion of this material (12.9 g, 37.9mmol) was dissolved in a mixture of dichloromethane and trifluoroaceticacid (100 mL each). This mixture was stirred at ambient temperature for2 h and then concentrated under vacuum. The residue was partitionedbetween chloroform (200 mL) and 50% aqueous potassium carbonate (200mL), and the aqueous layer was extracted with chloroform (3×200 mL). Thecombined chloroform layers were dried over anhydrous sodium sulfate andconcentrated under vacuum, leaving 8.66 g (95% yield) of pale yellowsolid (¹H NMR (d₄-methanol, 300 MHz) 3.15-3.35 (m, 4H), 3.50-4.20 (m,6H), 6.51 (d, 1H), 7.17 (d, 1H); MS m/z 241 (M+H)).

EXAMPLE 8 Synthesis of 3,7-diazabicyclo[3.3.1]nonane-3-carboxylic acidtert-butyl ester

Example 8 relates to the synthesis of3,7-diazabicyclo[3.3.1]nonane-3-carboxylic acid tert-butyl ester (orN-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane), which wasprepared according to the following techniques:

7-Benzyl-3,7-diazabicyclo[3.3.1]nonane-3-carboxylic acid tert-butylester (orN-benzyl-N′-(tert-butoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonane)

7-Benzyl-3,7-diazabicyclo[3.3.1]nonane-3-carboxylic acid tert-butylester was prepared according to procedures set forth by Stead et al. inOrg. Lett. 7(20): 4459 (2005).

3,7-Diazabicyclo[3.3.1]-3-carboxylic acid tert-butyl ester

7-Benzyl-3,7-diazabicyclo[3.3.1]nonane-3-carboxylic acid tert-butylester (0.49 g, 1.6 mmol) was dissolved in methanol (20 mL) and 20%Pd(OH)₂/C (wet) (˜2 g) was added under a nitrogen atmosphere. Thismixture was warmed to about 50° C. and shaken for 2 h under 55 psi ofhydrogen. The resulting mixture was filtered and concentrated to give0.32 g (94% yield) of the title compound (MS m/z 227 (M+H)).

EXAMPLE 9 Synthesis ofN-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane trifluoroacetate

Example 9 relates to the synthesis of(3,7-diazabicyclo[3.3.1]non-3-yl)-furan-2-ylmethanone trifluoroacetate(or N-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonanetrifluoroacetate), which was prepared according to the followingtechniques, illustrative of the coupling reaction used to makeheteroaromatic amides of 3,7-diazabicyclo[3.3.1]nonane:

3,7-Diazabicyclo[3.3.1]non-3-yl)-furan-2-yl methanone trifluoroacetate(or N-(furan-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonanetrifluoroacetate)

Furan-2-carboxylic acid (0.032 g, 0.29 mmol) was combined withtriethylamine (0.870 mmol, 0.121 mL) in dry dichloromethane (1 mL) andHBTU (0.11 g, 0.29 mmol) was added. A solution of3,7-diazabicyclo[3.3.1]-3-carboxylic acid tert-butyl ester (0.059 g,0.26 mmol) in dichloromethane (0.5 mL) was added, and the mixture wasstirred at ambient temperature overnight. The mixture was treated with10% aqueous sodium hydroxide and extracted with chloroform (2×2 mL). Thecombined organic extracts were washed with water (2×1 mL), andconcentrated. The resulting residue was dissolved in DMF (0.3 mL) andpurified by HPLC (acetonitrile/water gradient). Fractions containing thedesired material were pooled and concentrated, leaving thetert-butoxycarbonyl-protected product. This material was dissolved in amixture of trifluoroacetic acid (0.5 mL) and dichloromethane (0.5 mL),and the mixture was stirred at ambient temperature for 1 h. Thevolatiles were removed by rotary evaporation, followed by high vacuumtreatment, to give 36 mg of an oil (41% yield) (¹H NMR (d₄-methanol, 300MHz) 2.10 (bs, 2H), 2.35 (bs, 2H), 3.30-3.45 (m, 4H), 3.55 (m, 2H), 6.65(m, 1H), 7.15 (d, 1H), and 7.75 (d, 1H). MS m/z 221 (M+H)).

EXAMPLE 10 Synthesis ofN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonanetrifluoroacetate

Example 10 relates to the synthesis of(3,7-diazabicyclo[3.3.1]non-3-yl)-5-chlorofuran-2-ylmethanonetrifluoroacetate (orN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonanetrifluoroacetate), which was prepared by a process similar to thatdescribed in Example 9, according to the following techniques:

5-Chlorofuran-2-carboxylic acid (0.96 g, 6.5 mmol) was combined withtriethylamine (21 mmol, 2.9 mL) in dry dichloromethane (10 mL), and HBTU(2.47 g, 65.1 mmol) was added. A solution of3,7-diazabicyclo[3.3.1]-3-carboxylic acid tert-butyl ester (1.5 g, 66mmol) in dichloromethane (5 mL) was added, and the mixture was stirredat ambient temperature overnight. The mixture was treated with 10%aqueous sodium hydroxide and extracted with chloroform (2×20 mL). Thecombined organic extracts were washed with water (2×10 mL), andconcentrated. The resulting residue was purified by columnchromatography on silica gel, eluting with an ethyl acetate in hexanegradient, to give the tert-butoxycarbonyl-protected product, as aviscous oil. This material was dissolved in a mixture of trifluoroaceticacid (20 mL) and dichloromethane (20 mL), and the mixture was stirred atambient temperature for 1 h. The volatiles were removed by rotaryevaporation, followed by high vacuum treatment, to give 1.38 g (57.5%yield) of viscous yellow oil (¹H NMR (d₄-methanol, 300 MHz) 2.00 (bs,2H), 2.15 (bs, 2H), 3.15-3.35 (m, 6H), 4.25 (m, 2H), 6.53 (d, 1H) and7.10 (d, 1H). MS m/z 255 (M+H)).

EXAMPLE 11 Tabular Spectral and Receptor Binding Data

The above illustrated amide coupling procedures were utilized to makethe compounds shown in Tables 1 and 2. In some cases, compounds weresynthesized on a scale sufficient to obtain nuclear magnetic resonance(NMR) data. In other cases, compounds were produced on a smaller scalein various kinds of parallel synthesis apparatus and were (structurally)characterized by LCMS only.

TABLE 1 Rat MS: α4β2 Human m/z ¹H NMR: CD₃OD, Structure Ki α4β2 Ki α7 Ki(M + H) 300 MHz

20 33 13000 207 δ 7.72 (d, 1H), 7.18 (d, 1H), 6.60 (t, 1H), 3.47-4.2 (m,8H), 3.2 (m, 2H)

26 160 ND; failed HTS 218 δ 9.00 (d, 2H), 8.20 (m, 2H), 3.7-4.0 (m, 3H),3.47-3.7 (m, 5H), 3.2 (m, 2H)

54 73 12000 287

53 220 3100 207

35 31 2900 252

19 19 3500 238

1.5 1.5 12000 287

33 28 91000 241 δ 7.17 (d, J = 0.61 Hz, 1H), 6.51 (d, J = 0.73 Hz, 1H),4.20- 3.50 (m, 6H), 3.35- 3.15 (m, 4H)

44 54 25000 221

230 43 3200 307

130 28 23000 221

17 44 ND; failed HTS 288

29 18 ND; failed HTS 287 δ 7.80 (s, 1H), 7.2 (s, 1H), 3.5-4.2 (m, 8H),3.20 (m, 2H)

140 40 ND; failed HTS 267

54 24 ND; failed HTS 319 δ 7.50 (s, 1H), 7.17 (m, 2H), 6.78 (m, 1H),6.60 (s, 1H), 3.95-3.76 (m, 4H), 3.70-3.58 (m, 2H), 3.32-3.08 (m, 4H)

260 86 12000 283

110 95 ND; failed HTS 273

150 84 ND; failed HTS 222

15 9.2 210000 222

24 14 56000 222

32 31 ND; failed HTS 222

61 29 160000 221 δ 7.38 (d, J = 1.8 Hz, 1 H), 6.55 (d, J = 1.8 Hz, 1 H),3.79 (m, 2 H), 3.45 (m, 2 H), 3.06 (m, 2 H), 2.89 (m, 2 H), 2.67 (m, 2H), 2.37 (s, 3H)

53 63 ND; failed HTS 250

353 100 ND; failed HTS 237 δ 7.55 (s, 1H), 6.7- 6.6 (m, 1H), 3.9 (s,3H), 3.85 (m, 2H), 3.75 (m, 2H), 3.65 (m, 2H), 3.15 (m, 4H)

1000 45 ND; failed HTS 289 δ 6.48 (s, 1H), 3.5- 4.0 (m, 6H), 3.3-3.1 (m,4H), 2.35 (s, 3H)

320 36 ND; failed HTS 275 δ 8.25 (s, 1H), 7.35 (s, 1H), 4.2-3.6 (m, 4H),3.55 (dd, 2H), 3.3-3.2 (m, 4H)

31 28 ND; failed HTS 286 δ 8.15 (s, 1H), 7.35 (s, 1H), 4.2-3.6 (m, 4H),3.5 (dd, 2H), 3.4-3.2 (m, 4H)

20 22 ND; failed HTS 299/301

140 51 ND; failed HTS 233 δ 7.58 (dd, J = 2, 0.5 Hz, 1H), 7.26 (dd, J =18, 11 Hz, 1H), 6.86 (dd, J = 2, 0.5 Hz, 1H), 5.70 (dd, J = 18, 1.5 Hz,1H), 5.32 (dd, J = 11, 1.5 Hz, 1H), 4.20-3.62 (m, 4H), 3.62-3.58 (m,2H), 3.25-3.18 (m, 4H)

43 21 ND; failed HTS 287 δ 7.81 (s, 1H), 7.08 (d, J = 1 Hz, 1H),4.18-3.62 (m, 4H), 3.59 (m, 2H), 3.30- 3.20 (m, 4H), 2.40 (t, J = 7 Hz,2H), 1.60- 1.44 (m, 4H), 0.95 (t, J = 7 Hz, 3H)

2.8 2.4 ND; failed HTS 241

8.3 16 ND; failed HTS 225

20 4.9 ND; failed HTS 366

35 27 ND; failed HTS 225 δ 7.60 (d, J = 2 Hz, 1H), 7.59 (d, J = 2 Hz,1H), 4.18-3.65 (m, 4H), 3.60 (m, 2H), 3.22 (m, 4H)

25 14 ND; failed HTS 232 δ 7.85 (d, J = 2 Hz, 1H), 6.95 (d, J = 2 Hz,1H), 4.25-3.63 (m, 4H), 3.60 (m, 2H), 3.24 (m, 4H)

21 9.7 ND; failed HTS 241 δ 7.83 (d, J = 1 Hz, 1H), 7.16 (d, J = 0.7 Hz,1H), 4.20-3.62 (m, 4H), 3.60 (m, 2H), 3.28-3.19 (m, 4H)

89 90 ND; failed HTS 208 δ 8.79 (d, J = 1.7 Hz, 1H), 6.80 (d, J = 1.7Hz, 1H), 4.12 (dd, J = 12, 7 Hz, 1H), 3.99 (dd, J = 12, 3 Hz, 1 H), 3.90(dd, J = 13, 8 Hz, 1H), 3.75 (dd, J = 13, 4 Hz, 1H), 3.58 (m, 2H), 3.24(m, 4H)

36 21 ND; failed HTS 225 δ 7.80 (d, J = 1 Hz, 1H), 7.78 (d, J = 1 Hz,1H), 4.21-3.62 (m, 4H), 3.58 (m, 2H), 3.21 (m, 4H)

140 48 ND; failed HTS 231

50 40 ND; failed HTS 232

65 14 ND; failed HTS 239 δ 6.24 (s, 1H), 4.17- 3.65 (m, 4H), 3.57 (m,2H), 3.19 (m, 4H), 2.34 (s, 3H)

51 130 ND; failed HTS 257

43 69 ND; failed HTS 208.3 δ 8.52 (d, J = 2 Hz, 1H), 6.96 (d, J = 2 Hz,1H), 4.15 (dd, J = 8, 12 Hz, 1H), 3.91 (m, 2H), 3.72 (dd, J = 4, 14 Hz,1H), 3.60 (m, 2H), 3.33-3.23 (m, 4H).

TABLE 2 Rat α4β2 Human MS: m/z ¹H NMR: CD₃OD, Structure Ki α4β2 Ki α7 Ki(M + H) 300 MHz

31 9.9  15000 221 δ 7.75 (d, 1H), 7.15 (d, 1H), 6.65 (m, 1H), 4.55 (m,2H), 3.55 (m, 2H), 3.3- 3.45 (m, 4H), 2.35 (bs, 2H), 2.1 (bs, 2H)

110 18  1700 232

79 17 ND; failed HTS 301

41 51 ND; failed HTS 301

100 42 ND; failed HTS 235

15 7.3 120000 255 δ 7.10 (d, 1H), 6.53 (d, 1H), 4.25 (m, 2H), 3.15-3.35(m, 6H), 2.15 (bs, 2H), 2.0 (bs, 2H)

33 180 ND; failed HTS 252

5.9 18 ND; failed HTS 302

87 210 ND; failed HTS 278 δ 7.18 (d, 1H), 6.36 (d, 1H), 4.56 (m, 2H),3.58 (m, 2H), 3.40-3.24 (m, 4H), 2.30 (m, 2H), 2.18 (s, 3H), 2.05 (m,2H)

68 96 ND; failed HTS 236

20 64 ND; failed HTS 236

9.5 21 ND; failed HTS 236

29 47 ND; failed HTS 236

25 83 ND; failed HTS 262

96 29 ND; failed HTS 255

6.4 4.6 ND; failed HTS 239

86 62 ND; failed HTS 300 δ 8.19 (s, 1H), 7.3 (s, 1H), 4.45 (d, 2H),3.6-3.2 (m, 6H), 2.27 (bs, 2H), 2.1-2.0 (m, 2H)

6.3 23 ND; failed HTS 333 δ 8.22 (d, J = 1 Hz, 1H), 7.50 (d, J = 1 Hz,1H), 7.27 (m, 2H), 6.90 (m, 1H), 4.55 (d, J = 13 Hz, 2H), 3.58 (m, 2H),3.42-3.30 (m, 4H), 2.31 (bs, 2H), 2.06 (m, 2H)

12 35 ND; failed HTS 287

4 1.6 ND; failed HTS 380

110 57 ND; failed HTS 239 δ 7.63 (dd, J = 4, 2 Hz, 1H), 6.62 (dd, J = 2,1 Hz, 1H), 4.37 (d, J = 14 Hz, 2H), 3.50 (m, 2H), 3.34 (m, 4H), 2.28(bs, 2H), 2.06 (m, 2H)

110 31 ND; failed HTS 246

13 5.2 ND; failed HTS 255

77 10 ND; failed HTS 255

7.5 5.2 ND; failed HTS 313/315 (CDCl₃) δ 6.95 (s, 1H), 4.60 (d, 2H),3.55 (d, 2H), 3.38 (m, 2H), 3.25 (d, 2H), 2.35 (s, 3H), 2.25 (m, 2H),2.05 (m, 2H)

560 28 ND; failed HTS 251

28 26 ND; failed HTS 222

28 14 ND; failed HTS 239

220 47 ND; failed HTS 245

35 8.7 ND; failed HTS 246

500 62 ND; failed HTS 253/505

370 85 ND; failed HTS 222 δ 8.09 (d, 1H), 7.40 (d, 1H), 3.65-3.23 (m,8H), 2.30 (m, 2H), 2.05 (m, 2H)

27 23 ND; failed HTS 246

12 1.7 ND; failed HTS 301

65 31 ND; failed HTS 236

52 30 ND; failed HTS 222 δ 8.53 (d, 1H), 6.90 (d, 1H), 4.60-4.20 (m,2H), 3.58-3.25 (m, 6H), 2.30 (m, 2H), 2.05 (m, 2H)

Summary of Biological Data

Compounds of Tables 1 and 2, representative of the present invention,exhibited inhibition constants (Ki values) at the rat and human α4β2subtypes in the ranges of 1 nM to 1000 nM and 1 nM to 220 nMrespectively, indicating high affinity for the α4β2 subtype. Ki valuesat the α7 subtype vary within the range of 1700 nM to 210,000 nM (inmany cases the compounds did not bind sufficiently in high through-putscreening at the α7 subtype to warrant Ki determination). These samecompounds exhibited relatively little functional activity at either thehuman muscle (1-25% of the maximal response to nicotine) or humanganglion (1-20% of the maximal response to nicotine) subtypes.

Certain exemplified compounds were assessed in the NOR task. Thus, bothN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane (FIG. 1)and N-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.1]nonane (FIG.2) were active in OR in rats, at 0.1 mg/kg and 0.3 mg/kg respectively.This provides evidence of the efficacy (and potency) of the compounds ofthe present invention in treating cognitive deficits, attentionaldisorders and dementias, and the potential of these compounds for humantherapy.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein. Allpatents and publications referred to herein are incorporated byreference in their entirety, for all purposes.

The invention claimed is:
 1. A method for treating Parkinsonism orParkinson's Disease in a patient in thereof, comprising administeringN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane, or apharmaceutically acceptable salt thereof, to said patient.
 2. The methodof claim 1, wherein theN-(5-chlorofuran-2-ylcarbonyl)-3,7-diazabicyclo[3.3.0]octane, or apharmaceutically acceptable salt thereof is administered in a dose rangeof from about 100 μg/kg to about 1 mg/kg per day.